Electromagnetic Induction (EMI). An EMI instrument another tool to locate man-made subsurface objects. The EMI is moved over the surface without coming in contact with the surface so it is not affected by the terrain. However, EMI results are affected by surface features including vehicles, reinforced concrete, and buildings and will not be used in the vicinity of above-ground obstructions. Data is displayed on a control unit and can be displayed in a color-coded contour map which can be provided by GPRS for interpretation by the client.